Double-acting safety initiator



Dec. 22, 1964 R. J. YoN

DOUBLE-ACTING SAFETY INI'IVIATOR 2 Sheets-Sheet l Filed Dec .ILM

INVENTOR.

ROBERT J. LYON ATTORNEYS.

Dec. 22, 1964 R. J. LYON 3,162,120

DOUBLE-ACTING SAFETY INITIATOR Filed Dec. 31, 1962 2 Sheets-Sheet 2 INVENTOR, ROBERT J. LYON 3,162,120 VPatented Dec. 22, 1964 3,162,120 DDUBLE-ACTENG SAFETY INIT IATOR Robert .1. Lyon, Silver Spring, Md., assigner to the United States of America as represented by the Secretary of the Navy Filed Dec. 31, 1962, Ser. No. 248,815 4 Claims. (Cl. 1412-18) (Granted under rFitle 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalities thereon or therefor.

This invention relates to actuation counters for counting the tiring impulses received by a mine to lire the same, and more particularly to a new and unique initiator unit therefor.

Actuation counters are pre-set and used in mines to count a pre-set number of impulses and after the last count arm or set off the mine. The impulses are the result of signals received by the mine control circuitry indicative of the proximity of vessels. These signals may be created by any of the well known proximity fuze devices such as mechanical, electronic, magnetic, capacitive, etc.

The counters heretofore have employed an initiator unit which, in response to proximity of a vessel, caused a wire to heat, thus allowing the wire to expand and subsequently start the actuation counter which counts one vessel.

This prior system had, among others, a major drawback. The counter was allowed to be started by the expansion only of the wire. If the wire broke or loosened up the timing mechanism could run down (counting a preset number of non-existent vessels), closing a detonator switch prematurely, and thereby endanger lives of those working with the mine.

The present invention is a double-acting initiator wherein the above defect is eliminated. In the present invention the timing mechanism is caused to start by the expansion and contraction of a Nichrome V wire. Upon the reception of a signal indicative of the proximity of a vessel the wire is caused to heat, thereby rotating a pair of notched drums allowing an initiating slide to move to an intermediate position and engage a slot in one of the drums. The movement of this slide also actuates a switch which interrupts current liow through the wire allowing it to cool. Upon the cooling of the wire the other of said pair of drums is caused to rotate allowing the initiating slide to move to a final position at which it actuates the timing mechanism. The two drums are inter-related by means of a shoulder on each and a torsion spring between them. When the lower drum is turned during expansion of the wire its shoulder turns the upper drum, but when the lower drum is returned during contraction of the wire the upper drum is not returned due to its engagement with the initiator slide. The torsion spring ips the upper drum back to its oiiginal position when the initiator slide is withdrawn at the end of the timing cycle.

It is therefore an object of this invention to provide a new and improved initiator unit.

Another object is to provide an initiator unit which overcomes the aforementioned deficiencies.

Another object of the invention is to provide a doubleacting initiator which starts operation of an actuation counter by the expansion and contraction of a Nichrome V wire.

A further object is the provision of a double-acting initiator which fails to operate its associated mechanisms if the time delay wire breaks or loosens.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same` becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a plan view of the invention;

FIG. 2 is an elevation view of the device of FIG. 1;

FIG. 3 is a sectional view taken along the line A-A of FIG. 1;

FIG. 4 is a sectional view taken along the line B-B of FIG. 1, illustrative of the engagement of the initiator slide with the drums; and Y FIGS. 5a through 5c lare diagrammatic illustrations of the engagement of the initiator slide with the drums.

Referring now to the drawing wherein like reference numerals indicate like or similar elements throughout the several views and more particularly to FIGS. 1 and 2 wherein there is shown a plan view and an elevation View, respectively, of the initiator unit. The initiator assembly consists of the top plate 2, riveted to an insulator plate 3 with a mica insulator 4 interleaved. The plate 3 has a channel 5 in which the wire 6 passes from one point of attachment on the shaft of the ratchet wheel 7 in the hole therein to another point of attachment on pin 8 in locked in relationship to therteeth 19 in arm 9, notches the actuator arm or gear segment lever 9. The channel 5 is made narrow and the depth is such that Vin a cross section thereof the Wire 6 would occupy the middle state of the area thus produced. The wire being closely conned Within the channel of insulating material any deviation from straightness would encounter contact with a rigid surface by the wire, if such were vthe result of shock or vibration. Under normal conditions the wire does not touch the walls of the channel, but the configuration employed offers a means of dampening and protection from sidewise distention.

The actuator arm 9 is pivoted on shaft 18. The pin 8 ne ratchet teeth and a click spring 11 has ya bent at portion that provides a pawl for the ratchet teeth of the ratchet wheel. A yoke portion 12 is formed on the end of the click spring and coacts with a groove 13 (FIG. 2)

in the ratchet wheel shaft to retain the ratchet wheel provide a means for tensioning the wire in steps for each ratchet tooth space kto take up any slack and also to bring the upper edge of hole 16 in actuator arm 9.against the pin 17 as will hereinafter become more apparent.

The actuator arm 9 is'pivoted on shaft 1S. The pin 8 is located close to the pivot 1S and the two teeth 19 formedv into the arm 9, which coact with the teeth in drum 21, are located further from the pivot 1S. Such a difference in the two distances acts to multiply the small magnitude of wire expansion in order to turn the drum 21 the desired'amount. For example and'not by way of limitation, a ratio of 5 to 1 has been found suitable.

Post 23 forms a pivot bearing for the drums or initiator cams 21 and 22 and is fastened into .the composite base of the initiator. The shank of the post forms a rivet member for assembling the parts 2, 3, 4 andan insulator plate 24 together. The insulator plate 24 is designed to cover any live riveting or projecting parts and insulate the same from the actuation counter, to which the initiator unit isjailixed. Y l

Drums 21. and 22 are arranged so that they arerinter- 25 and 25 in each of the drums, and spring recesses 21 and 28 in each. Drum 22 is capable of a limited amountr of rotation on the thimble 29 relative to drum 21. The

amount of rotation is dependent upon the angularrspace between the edges of the interlocking means, which consist of reduced diameters 31 and 32 that are in theiform of,v Y

a key in one drum and a coacting notch in the other, being held together by the resiliency of torsion spring 33 which has two bent legs. One of said'legs restsinspring recess 27 and the other inV spring recess 28'as shown in FIG. 4'.W

The actuator arm 9 is held in the position shown in FIG. l by the tension in the wire 6. Spring 34 tends to rotate the arm in a direction opposite to that of the Nichrome V wire, the total magnitude of rotation being limited by the hole 16 in arm 9 and the pin 17 which engages this hole. The spring is coiled around hub 35, aftixed to arm 9, and has one leg 36 against a balancing stud 37. A second spring leg 38 is tensioned against an upwardly bent terminal tab 39 formed in plate 41 which forms the support plate for stud or pivot 18 upon which the actuator arm pivots. Plate 41 is riveted to the insulator plate 3 with a portion of the mica 4 interleaved.

In FIG. 1 there is shown notch 26 tilted in its rest position with the release or initiator slide 42 against the outer stainless steel band 43 of drum 22. The notch 25 is in a relationship so that when cams Z1 and 22 are turned counterclockwise in unison the right edge of notch 25 will be under the initiator slide edge before the left edge of notch 26 has departed from the slide. As shown in FIG. 4 the notch engaging portion of slide 42 is so designed that thefinger 44 which engages notch 26 is longer than the finger 45 which engages notch 25.

The initiator slide has afixed thereto an arm 46 which, when the slide engages the notches in both drums, opens the switch 47 that is mounted on the plate 2. An electrical conductor 48 connects terminal 49 of switch 47 to lug 51 which is affixed to click spring 11. Another conductor 52 connects terminal 53 or" switch 47 to a control switch 54, from there to battery 55 and thence through a third conductor 56 to terminal tab 39 on plate 41. When the switch contacts of switch 47 are closed an electrical circuit is completed upon closure of control switch 54 allowing current to liow from battery 55 through conductor 56 to tab 39, through plate 41 to pivot 18, through arm 9 to pin 8, through Nichrome V wire 6 to the shaft of the ratchet wheel 7, through yoke 12 of the click spring 11 to terminal 51, through conductor 48 to terminal 49, through switch 47 to terminal 53, through conductor 52 to control switch 54 and back to the battery 55.

Initiator slide 42 is supported by supports 57 and 58. Mechanically connected to the slide is a timing mechanism 59 and a detonator switch 61. The function of these elements will be hereinafter explained.

FIG. 3 is a sectional view taken along the lines A-A of FIG. 1. This figure is included to enable those skilled in the art to obtain a better understanding of the unique drums assembly.

A diagram is shown in FIGS. Saz-c, inclusive, which serves to illustrate the position of each drum relative to the fingers of the slide 42, by top diagrammatic views of each drum and finger, throughout the operation of the initiator unit. When switch 54 is open, i.e., when no signal has been received indicative of the proximity of a vessel, the relationship is as shown in FIG. 5a. Upon the reception of a signal indicative of an approaching VesselV switch 54 closes which allows current to flow through the Nichrome V wire, thus heating it and causing it to expand. When this wire expands arm 9 is caused to rotate in a clockwise direction, by action of spring 34, moving the drums into the positions shown in FIG. 5b. The wire motion is transmitted to drum 21 by arm 9 and due to the interlock arrangement between drums 21 and 22, the shoulder of drum 21 causes drum 22 to rotate also. The initiator slide finger 44 drops into the slot 26 due to the action of spring 62.

When the drums reach the intermediate position shown in FIG. 5b the arms 46 on slide 42 opens switch 47 thus interrupting current flow through the Nichrome V wire and allowing it to cool. As the wire cools it contracts, rotating arm 9, against the action of spring 34, which rotates drum 21 in a clockwise direction. Drum 22 is not clockwise rotated since it is held in position by finger 44. The resulting action allows slots and 26 to align and the finger 45 of the initiator slide moves into the slot 2 5 as shown n FIG. 5c. This final movement of the slide mechanically starts, through connection 64, the timing mechanism 59 of the actuation counter. After a predetermined time the timing mechanism retracts the slide by rotation of finger 55 against portion 66 of the slide 42 allowing switch 47 to close and drum 22 to return to its original position by action of torsion spring 33, thereby resetting the initiator unit preparing it to again operate upon the reception of a signal indicating an approaching vessel.

In its use in an actuation counter the initiator unit allows the slide 4Z to engage the slots in both drums. When the slide so moves the finger 53 thereof may engage detonator switch 61 thus firing the mine. However, if the counting mechanism (not shown) of the actuation counter is set at any number higher than one tne finger 63 is allowed to pivot on hinge 67 by action of the counting mechanism, so that it does not engage switch 61 until the initiator unit has operated and recycled the pre-set number of times. Upon the last count the linger 63 wiil engage switch 61.

The condition switch 54 which starts the action of the initiator is diagrammatically representative of a proximity switch and it should be realized that there may be other such switches responsive to other conditions.

The drums and actuating arm herein described may each be statically balanced to prevent possible failures due to shock.

Although the initiator unit has been described in connection with an actuation counter, the device may be readily used where a fail-safe initiating device is required. In such case the switch 61 or others may be operated by finger 63 without the intervention of the counting mechanism. In such a case the slide could be reset manually or by a timing mechanism as used herein.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. t is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specially described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A double-acting safety initiator unit comprising in combination, an extensible wire connected in an electrical circuit for heating said wire, said circuit including a normally-closed rst switch and a normally-open second switch, said wire being connected to a xed support at one end and affixed to a gear means at its other end, said gear means being spring biased to assume a first position, said gear means being operatively connected to the first of a pair of cylindrical drums, said drums being resiliently interlocked for rotary movement together and relative movement therebetween, each of said drums having a slot parallel to the axis thereof, and a spring-urged slide means abutting said drums adapted, when said slots are in alignment, to engage said slots and to actuate said first switch whereby, when said second switch is closed current iiows in said circuit, heating and thereby expanding said wire to permit said gear means to be moved from its first position by the associated spring biasing means, thus rotating the first of said drums and allowing said slide means to assume an intermediate position engaging the slot in the second of said drums, thereby opening said first switch interrupting current fiow through said wire, allowing said wire to cool and exert a tensional force on said gear means for rotating the rst of said drums to its initial position causing alignment of said slots and allowing said slide means to assume a final position engaging both slots in said pair of drums.

2. A double-acting safety initiator unit as in claim l wherein said slide means, upon engagement with both slots, operates a load device.

3. A double-acting safety initiator unit as in claim l wherein said extensible wire is a Nichrome wire.

4. A safety arming device comprising a spring urged arming member, a base, means for mounting the arming member on said base for slideable movement from an initial safe position to an intermediate position and thereafter to a final armed position, a locking drum rotatable about an axis and having a slot therein parallel to said axis for receiving a irst end portion of said arming member as the arming member is moved to the armed position, a second locking drum mounted for rotary movement on an axis coincidental with the axis of said rstnamed drum and adapted to be rotated unitarily by said first-named drum, said second drum having a slot therein parallel to said coincidental axis and normally out of line with a second end portion of said arming member and adapted to be engaged by said second portion when the iirst and second drums have been rotated to a moved position and the slot of the second drum is in alignment with the slot of said tirst drum, a gear means operatively connected to said irst drum for rotating said rst and second drums from an initial position to a moved position, resilient means secured to said gear means for moving the gear means and said lirst drum from said initial position to said moved position, an extensible wire secured under tension to said gear means in opposition to said resiiient means for maintaining the gear means in said initial position until the wire has become extended by heat caused by the passage of an electrical current through said wire, a pair of normally closed contacts, means on said arming member for opening said contacts as the arming member moves into said intermediate position, a power circuit including said contacts for heating said Wire until the Wire has been extended suiciently for the contacts to be opened, a pair of complementary stop members on said drums, a second resilient means interconnecting said drums for causing the drums to be urged against said stopmembers whereby the drums are moved integrally from the initial position to said moved position by said tiret-named resilient means and said gear means as the wire is extended, said arming member moving from the initial safe position to said intermediate position as the second end portion of said arming'member enters the slot in said second drum, said second resilient means allowing the @first-named drum to be rotated reversely from the moved position by the first-named resilient means and said gear means upon contraction of said Wire while the second drum is locked in the moved position by the second end portion of the arming member until the first-named drum has moved to said initial position whereby the slot formed therein is engaged by the rst-named end portion of the arming member as the arming member moves from said intermediate position to said final armed position.

References Cited bythe Examiner UNITED STATES PATENTS SAMUEL FEINBERG, Primary Examiner. 

1. A DOUBLE-ACTING SAFETY INITIATOR UNIT COMPRISING IN COMBINATION, AN EXTENSIBLE WIRE CONNECTED IN AN ELECTRICAL CIRCUIT FOR HEATING SAID WIRE, SAID CIRCUIT INCLUDING A NORMALLY-CLOSED FIRST SWITCH AND A NORMALLY-OPEN SECOND SWITCH, SAID WIRE BEING CONNECTED TO A FIXED SUPPORT AT ONE END AND AFFIXED TO A GEAR MEANS AT ITS OTHER END, SAID GEAR MEANS BEING SPRING BIASED TO ASSUME A FIRST POSITION, SAID GEAR MEANS BEING OPERATIVELY CONNECTED TO THE FIRST OF A PAIR OF CYLINDRICAL DRUMS, SAID DRUMS BEING RESILIENTLY INTERLOCKED FOR ROTARY MOVEMENT TOGETHER AND RELATIVE MOVEMENT THEREBETWEEN, EACH OF SAID DRUMS HAVING A SLOT PARALLEL TO THE AXIS THEREOF, AND A SPRING-URGED SLIDE MEANS ABUTTING SAID DRUMS ADAPTED, WHEN SAID SLOTS ARE IN ALIGNMENT, TO ENGAGE SAID SLOTS AND TO ACTUATE SAID FIRST SWITCH WHEREBY, WHEN SAID SECOND SWITCH IS CLOSED CURRENT FLOWS IN SAID CIRCUIT, HEATING AND THEREBY EXPANDING SAID WIRE TO PERMIT SAID GEAR MEANS TO BE MOVED FROM ITS FIRST POSITION BY THE ASSOCIATED SPRING BIASING MEANS, THUS ROTATING THE FIRST OF SAID DRUMS AND ALLOWING SAID SLIDE MEANS TO ASSUME AN INTERMEDIATE POSITION ENGAGING THE SLOT IN THE SECOND OF SAID DRUMS, THEREBY OPENING SAID FIRST SWITCH INTERRUPTING CURRENT FLOW THROUGH SAID WIRE, ALLOWING SAID WIRE TO COOL AND EXERT A TENSIONAL FORCE ON SAID GEAR MEANS FOR ROTATING THE FIRST OF SAID DRUMS TO ITS INITIAL POSITION CAUSING ALIGNMENT OF SAID SLOTS AND ALLOWING SAID SLIDE MEANS TO ASSUME A FINAL POSITION ENGAGING BOTH SLOTS IN SAID PAIR OF DRUMS. 